Biosorption of Cu (II) onto chemically modified waste mycelium of Aspergillus awamori: Equilibrium, kinetics and modeling studies

The biosorption potential of chemically modified waste mycelium of industrial xylanase-producing strain Aspergillus awamori for Cu (II) removal from aqueous solutions was evaluated. The influence of pH, contact time and initial Cu (II) concentration on the removal efficiency was evaluated. Maximum biosorption capacity was reached by sodium hydroxide treated waste fungal mycelium at pH 5.0. The Langmuir adsorption equation matched very well the adsorption equilibrium data in the studied conditions. The process kinetic followed the pseudo-firs order model

Hexavalent chromium removal by waste mycelium of Aspergillus awamori

In this study, the Cr(VI) removal potential of waste mycelium from the industrial xylanase-producing strain Aspergillus awamori was evaluated. It was determined by FTIR analysis that amino groups from the major fungal wall constituents, chitin and chitosan, played a key role in the metal binding process. The effect of pH, initial ion concentration, temperature and amount of biomass on the removal was also studied. The removal efficiency increased with decreasing pH and increasing temperature and amount of biomass. The mechanism of Cr(VI) removal by A. awamori can be explained by a two-stage process involving an initial adsorption stage followed by a reducing stage. The removal process was described by a second-order polynomial and the optimal process parameters for attaining Rmax 94.4 % in 48 h were predicted, i.e., pH 1.5 and t = 40 °C. From both economic and ecological points of view, a promising possibility for the utilization of waste industrial mycelium of A. awamori as a low-cost Cr(VI) removal agent was proposed

JSCS–3987 Original scientific paper Hexavalent chromium removal by waste mycelium

Abstract: In this study, the Cr(VI) removal potential of waste mycelium from the industrial xylanase-producing strain Aspergillus awamori was evaluated. It was determined by FTIR analysis that amino groups from the major fungal wall constituents, chitin and chitosan, played a key role in the metal binding process. The effect of pH, initial ion concentration, temperature and amount of biomass on the removal was also studied. The removal efficiency increased with decreasing pH and increasing temperature and amount of biomass. The mechanism of Cr(VI) removal by A. awamori can be explained by a two-stage process involving an initial adsorption stage followed by a reducing stage. The removal process was described by a second-order polynomial and the optimal process parameters for attaining R max 94.4 % in 48 h were predicted, i.e., pH 1.5 and t = 40 °C. From both economic and ecological points of view, a promising possibility for the utilization of waste industrial mycelium of A. awamori as a low-cost Cr(VI) removal agent was proposed

Anodic Stripping Differential Alternative Pulses Voltammetry and Applications

International audienc

Electrochemical sensor based on <I>Arthrobacter globiformis</I> for cholinesterase activity determination

International audienceThe sensors applied recently for determination of cholinesterase activity are mostly enzymatic amperometric sensors, in spite of their disadvantages: short life-time at ambient temperature, instability of the response, interferences, as well as passivation of the electrode surface. In the present paper a new approach for determination of cholinesterase activity was proposed, overcoming the main drawbacks of the analysis performed with amperometric enzymatic sensors. Instead of the immobilization of enzymes on a conducting electrode surface, whole cells of Arthrobacter globiformis, containing choline oxidase were fixed on a Clark type oxygen probe. Current proportional to bacteria respiration is registered as a sensor response. The application of whole cells of bacteria as a sensing element permits to achieve high stability of the response and long life-time of the sensor at ambient temperature, due to the conservation of the enzyme in its natural micro-environment inside the immobilized cells. The proposed sensor keeps its functionality more than 7 weeks stored in deionized water at ambient temperature. For the first 2 weeks the amplitude of the response decreases with only 10% and at the end of the studied 7 weeks period the response was 50% of the initial. The other advantages of the proposed sensor are: the dissolved oxygen is used as a mediator which concentration can be reliably and interferences free measured by the aim of a Clark type oxygen probe applied as a transducer; reproducible bacterial membranes can be elaborated by filtration of resuspended bacterial culture after preliminary determination of its activity; application of membranes containing lyophilized bacteria capable to be conserved infinitely long time and activated just before their application; negligible cost compared with the sensors based on immobilized enzymes. The steady-state response of the proposed bacterial sensor to choline obtained in 200 s is linear in the investigated concentration range up to 2 × 104 mol dm3, with detection limit of 8 × 108 mol dm3 and sensitivity of 4 × 101 μA cm3 mol1, at pH 6, temperature of 25 °C and stirring rate of 300 rpm. Choline is formed as a result of the catalytic hydrolysis (depending on the cholinesterase activity) of the substrate acetylcholine. Linear calibration graph for cholinesterase activity determination was obtained in the range up to 11 mU cm3, with a slope of 1.97 × 102 μA cm3 mU1, at pH 6, temperature of 25 °C and stirring rate of 300 rpm. The tests with reconstituted lyophilized serum with known activity used as a control sample confirm the accuracy of the proposed method. The relative error of the determination was only 2.82%

Novel composite biosorbent from Bacillus cereus for heavy metals removal from aqueous solutions

Waste biomass from Bacillus cereus immobilized in sodium alginate and co-immobilized with activated carbon or with bentonite into alginate gel was studied for Pb(II), Cd(II) and Hg(II) removal from aqueous solutions. The composite biosorbent consisting of waste B. cereus biomass co-immobilized with activated carbon into alginate beads was selected as the most prospective for heavy metals removal. Immobilization increased both the removal capacity and the mechanical strength of the biosorbent. Major process parameters were optimized and maximum removal efficiency of 92.13% was reached for Pb(II) ions at pH 5.0, biosorbent dosage 2 g/L, temperature 25 °C, agitation speed 120 rpm for 120 min